# Bulletin of the American Physical Society

# 2021 Fall Meeting of the APS Prairie Section

## Volume 66, Number 14

## Thursday–Saturday, November 11–13, 2021; Lewis University, Romeoville Illinois (Hybrid options available)

## Session C01: High Energy Physics |
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Chair: Bryce Littlejohn, Illinois Tech |

Saturday, November 13, 2021 10:45AM - 10:57AM |
C01.00001: Tau electromagnetic energy loss and tau polarization for very high energy tau leptons Diksha Garg, Carlos A. Argu\"elles, Sameer Patel, Mary Hall Reno, Ibrahim Safa The neutrino interaction length scales with energy, and becomes comparable to Earth’s diameter above PeV energies. At such high energies, the tau's short lifetime leads to energetic regenerated tau neutrino flux, $\nu_\tau\to\tau\to \nu_\tau$, within the Earth. The next generation of neutrino experiments aim to detect ultra-high energy neutrinos, and many of them rely on detecting either the regenerated tau neutrino, or the tau decay shower. Both of these signatures are affected by polarization of the tau through the energy distribution of the secondary particles produced from the tau's decay. While $\tau$'s produced in weak interactions are nearly 100\% polarized, it is expected that $\tau$'s experience depolarization due to electromagnetic energy loss in the Earth. In this talk, we quantify the depolarization of $\tau$'s in electromagnetic energy loss. Tau depolarization can be directly implemented in Monte Carlo simulations such as NuPyProp, TauRunner and other tau neutrino propagation codes. [Preview Abstract] |

Saturday, November 13, 2021 10:57AM - 11:09AM |
C01.00002: Silicon Module Testing for the Compact Muon Solenoid Forward Pixel Upgrade Alexander Thielen In order to strengthen results of the Large Hadron Collider, higher luminosities will be used in future runs. This will result in larger particle flux and radiation to the Silicon Pixel Detector of the Compact Muon Solenoid. To maintain the precision of particle tracking, the detector must undergo an upgrade. Each of the silicon modules must pass numerous quality assurance tests to ensure the accuracy in the path of tracked particles. [Preview Abstract] |

Saturday, November 13, 2021 11:09AM - 11:21AM |
C01.00003: Revisiting Combinatorial Ambiguities in Dilepton t ̄t Event Topologies with Neural Networks Zhongtian Dong, Haider Alhazmi, Li Huang, Jeong Han Kim, Kyoungchul Kong, David Shih We revisit with machine learning algorithms the combinatorial problem in SUSY-like events with two invisible particles at the LHC. As a concrete example, we illustrate our procedure with the dilepton $t \bar t$ events. We first reproduce results using several existing methods and compare them against performance of various machine learning algorithms. In particular, we investigate performance of attention-based network, which exploits permutation symmetry in the problem. We then consider the general case when the underlying mass spectrum is unknown, and no kinematic endpoint information is available. We demonstrate that the efficiency for selecting the correct partition is greatly improved by utilizing the machine learning techniques. [Preview Abstract] |

Saturday, November 13, 2021 11:21AM - 11:33AM |
C01.00004: Investigation of CP-Violation in the Top-Higgs Yukawa Interaction via High-Energy Muon Collisions Morgan Cassidy, Ian Lewis, Kyoungchul Kong, Cosmos Dong, Ya-Juan Zheng, Jenny Zhang The Standard Model of particle physics, though remaining a consistent theory with the discovery of the Higgs boson, fails to address several questions about nature, such as the accelerated expansion of the universe, dark matter, and the asymmetry of matter and anti-matter. Of interest, and a goal of particle physics, is to look for new interactions in order to provide explanation to these questions. This project studies a new source for CP-violating interactions via the top quark and Higgs through high-energy muon collisions. The signal processes include $ \mu\mu$ $\rightarrow$ $t\bar{t}h$, $ \mu\mu$ $\rightarrow$ $t\bar{t}h\nu\nu$, and $ \mu\mu$ $\rightarrow$ $t\bar{b}h\mu\nu$ decaying semi-leptonically, and are simulated using MadGraph5\_aMC@NLO. A CP-Violating model is incorporated into the MadGraph5\_aMC@NLO framework to account for a non-zero CP phase, unlike what is predicted in the Standard Model for the top-Higgs Yukawa interaction. The current focus studies kinematic distributions for a CP angle set at $\frac{\pi}{2}$ and $-\frac{\pi}{2}$. Looking forward, the signal processes will be set to decay hadronically and leptonically, and ultimately, this study looks to determine limits on the CP angle of the top-Higgs Yukawa interaction. [Preview Abstract] |

Saturday, November 13, 2021 11:33AM - 11:45AM |
C01.00005: Top-Higgs Interactive Simulations through MadGraph5\_aMC@NLO and Future Investigations of Muon Colliders Yanzhe Zhang, Morgan Cassidy, Ian Lewis, Kyoungchul Kong, Yajuan Zheng, Zhongtian Dong Particle colliders accelerate the discoveries and verification of the theoretical predictions of particles and the completeness of the Standard Model. Yet, the Standard Model still has its limitations including but not only the exclusion of gravity, the lack of solutions to the expanding universe in acceleration, and the problem of matter-antimatter asymmetry. Among all the fundamental particles within the Standard Model, top-quark and Higgs boson, as the most and second heaviest fundamental particles, are of particular interest. Therefore, we especially concentrate our focus on the top-Higgs interactions in a new type of proposed leptonic collider: the muon collider. Simulations of $\mu^+\mu^-$ collisions are done in both the Standard Model and a CP-violating model through MadGraph5\_aMC@NLO and with smearing effects applied on the analyses of the cross-section variations and kinematic distributions as well as multiple cutoffs to find an analogy of the muon collider. With the study being further pursued, we hope to find more efficient cuts in order to maximize the signal-to-background significance and investigate the ability of a muon collider to detect CP violation in the top-Higgs interactions. [Preview Abstract] |

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